In the course of extended basic and applied research into the preservation and processing of various perishable foodstuffs, biological tissue, and the like in a low temperature zone below 0.degree. C., the inventors established so-called "super CFP (Controlled Freezing Point; CFP means the temperature zone between 0.degree. C. and freezing point of a food or the like and super CFP means the temperature zone between freezing point and breaking point of it." preservation and processing techniques characterized in that various perishable foodstuffs or the like are preserved and processed in a non-freezing region below the freezing point, and have previously succeeded in developing methods for preserving various perishable foods and the like under such super CFP conditions, as well as methods for preserving and processing vegetables, fruits, seafood, and other such perishable foods and the like by utilizing super-cold water. As a result of research into these methods, the inventors discovered that it is possible to keep just-harvested vegetables, fruits, seafood, and other such perishable foods and the like at a high level of freshness during their storage by subjecting said perishable food or the like to a cooling treatment under specific super-cold conditions in a non-freezing region below the freezing point. The inventors also discovered that these methods are extremely useful especially as methods for preserving and processing vegetables, fruits, seafood, and other such perishable food or the like.
In general, among the various foods and the like, it is particularly important for vegetables and fruits, being natural products, to be fresh, just as with seafood and the like. The continuous maintenance of freshness and quality are considered vital throughout the course of distribution, from the place where these foods are produced to the market, and from the market to the place of sale.
Thus, the ideal way to supply products in a fresh and high-quality form would be via a "cold chain" that comprises specific low-temperature conditions, from the production stage (the site of harvest) to the consumption stage. In actual practice, however, the preservation conditions are often less than adequate along the distribution channels, which is due to distribution cost considerations, low-temperature preservation technology limitations, and so on.
As the mass production and mass consumption of foods becomes increasingly common, consumer needs are becoming more diverse, and many different types of product are appearing on the market in response to this diversification. This has been accompanied by a trend in which consumers demand products of lower cost and higher quality. There is also growing interest in natural foods when it comes to vegetables, fruits, seafood, and other such perishable food and the like, which has created a strong demand for high-quality products that are fresh and high in nutritional value.
As mentioned above, vegetables, fruits, seafood, and other such perishable food and the like are harvested and produced in many different locations as agricultural and marine products, and in most cases reach the consumer after first going through a market and a retail outlet, so even today, with all of our sophisticated technology for preserving said perishable food or the like, it is still quite difficult to maintain that fresh-picked or fresh-caught flavor and freshness over an extended period. For instance, even if the distribution time could be specially shortened to ensure a good state of preservation, the cost at the current time would be tremendous, and except for some high-end products, this would be an impractical method for the general distribution of perishable foods.
Low-temperature preservation methods, low-temperature preservation equipment, low-temperature transportation technology, and the like used in the course of distribution have been studied from various angles in the past in an effort to improve this situation even a little, and the result up to this point has; been the development of widely diverse techniques. Typical examples of these are CA storage and MA storage (Shokuhin Ryutsu Gijutsu, Vol. 22, No. 11 (1993)), although various other methods have also been developed and improvements made. Still, there is generally a precipitous decline in the freshness of perishable foods immediately after their harvest, just as with the decrease in freshness in the course of distribution. Specifically, with fruits and vegetables, there is a rapid decomposition of useful components such as vitamin C and other nutrients, chlorophyll, and so on, and with seafood, there is a decrease in the K value (an index of freshness) caused by the rapid decomposition of ATP, and since these and other deteriorations in quality inevitably occur, unless some new technique is developed that will allow such decreases in freshness immediately after harvest to be reliably suppressed, it will remain impossible to maintain a state of high freshness close to that immediately after harvest.